8310066: Improve test coverage for JVMTI GetThreadState on carrier and mounted vthread

Reviewed-by: sspitsyn, cjplummer

Author: Alex Menkov

test/hotspot/jtreg/serviceability/jvmti/vthread/GetThreadStateMountedTest/GetThreadStateMountedTest.java

@@ -0,0 +1,331 @@
+/*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * @test
+ * @bug 8309612 8310584
+ * @summary The test verifies that JVMTI GetThreadState function reports expected state
+ *          for mounted (pinned) virtual thread and its carrier thread
+ * @requires vm.jvmti
+ * @requires vm.continuations
+ * @run main/othervm/native
+ *      -agentlib:GetThreadStateMountedTest
+ *      GetThreadStateMountedTest
+ */
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.locks.LockSupport;
+
+/**
+ * The test implements different scenarios to get desired JVMTI thread states.
+ * For each scenario the test also checks states after carrier and virtual threads suspend/resume
+ * and after virtual thread interrupt.
+ * Special handling is required for WAITING state scenarios:
+ * Spurious wakeups may cause unexpected thread state change and this causes test failure.
+ * To avoid this, the test thread should be suspended (i.e. carrier and/or mounted virtual thread is suspended).
+ */
+public class GetThreadStateMountedTest {
+
+    static final int JVMTI_THREAD_STATE_RUNNABLE                 = 0x0004;
+    static final int JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTER = 0x0400;
+    static final int JVMTI_THREAD_STATE_WAITING                  = 0x0080;
+    static final int JVMTI_THREAD_STATE_WAITING_INDEFINITELY     = 0x0010;
+    static final int JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT     = 0x0020;
+    static final int JVMTI_THREAD_STATE_IN_OBJECT_WAIT           = 0x0100;
+    static final int JVMTI_THREAD_STATE_SLEEPING                 = 0x0040;
+    static final int JVMTI_THREAD_STATE_PARKED                   = 0x0200;
+    static final int JVMTI_THREAD_STATE_IN_NATIVE                = 0x400000;
+
+    static void runnable() throws Exception {
+        TestStatus status = new TestStatus("JVMTI_THREAD_STATE_RUNNABLE");
+        CountDownLatch ready = new CountDownLatch(1);
+        final boolean[] stopFlag = new boolean[1];
+        Thread vthread = createPinnedVThread(() -> {
+            ready.countDown();
+            int i = 0;
+            while (!stopFlag[0]) {
+                if (i < 200) {
+                    i++;
+                } else {
+                    i = 0;
+                }
+            }
+        });
+        vthread.start();
+        ready.await();
+        testThreadStates(vthread, false, true, JVMTI_THREAD_STATE_RUNNABLE);
+        stopFlag[0] = true;
+        status.print();
+    }
+
+    static void blockedOnMonitorEnter() throws Exception {
+        // JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTER
+        // Thread is waiting to enter a synchronized block/method or,
+        // after an Object.wait(), waiting to re-enter a synchronized block/method.
+        TestStatus status = new TestStatus("JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTER");
+        CountDownLatch ready = new CountDownLatch(1);
+        final Object syncObj = new Object();
+        Thread vthread = createPinnedVThread(() -> {
+            ready.countDown();
+            synchronized (syncObj) {
+            }
+        });
+        synchronized (syncObj) {
+            vthread.start();
+            ready.await();
+            Thread.sleep(500); // wait some time to ensure the thread is blocked on monitor
+            testThreadStates(vthread, false, true, JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTER);
+        }
+        status.print();
+    }
+
+    static void waiting(boolean withTimeout) throws Exception {
+        // JVMTI_THREAD_STATE_WAITING
+        // Thread is waiting.
+        // JVMTI_THREAD_STATE_WAITING_INDEFINITELY
+        // Thread is waiting without a timeout. For example, Object.wait().
+        // JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT
+        // Thread is waiting with a maximum time to wait specified. For example, Object.wait(long).
+        TestStatus status = new TestStatus(withTimeout
+                                           ? "JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT"
+                                           : "JVMTI_THREAD_STATE_WAITING_INDEFINITELY");
+        CountDownLatch ready = new CountDownLatch(1);
+        // Test thread exits by InterruptedException,
+        // stopFlag is to handle spurious wakeups.
+        final boolean[] stopFlag = new boolean[1];
+        final Object syncObj = new Object();
+        Thread vthread = createPinnedVThread(() -> {
+            synchronized (syncObj) {
+                try {
+                    ready.countDown();
+                    while (!stopFlag[0]) {
+                        if (withTimeout) {
+                            syncObj.wait(60000);
+                        } else {
+                            syncObj.wait();
+                        }
+                    }
+                } catch (InterruptedException ex) {
+                    // expected after testThreadStates
+                }
+            }
+        });
+        vthread.start();
+        ready.await();
+
+        // Suspend test thread in "waiting" state.
+        suspendWaiting(vthread);
+
+        int expectedState = JVMTI_THREAD_STATE_WAITING
+                | JVMTI_THREAD_STATE_IN_OBJECT_WAIT
+                | (withTimeout
+                    ? JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT
+                    : JVMTI_THREAD_STATE_WAITING_INDEFINITELY);
+        testThreadStates(vthread, true,  true, expectedState);
+        // signal test thread to finish (for safety, Object.wait should throw InterruptedException)
+        synchronized (syncObj) {
+            stopFlag[0] = true;
+            syncObj.notifyAll();
+        }
+        status.print();
+    }
+
+    static void sleeping() throws Exception {
+        // JVMTI_THREAD_STATE_SLEEPING
+        // Thread is sleeping -- Thread.sleep.
+        // JVMTI_THREAD_STATE_PARKED
+        // A virtual thread that is sleeping, in Thread.sleep,
+        // may have this state flag set instead of JVMTI_THREAD_STATE_SLEEPING.
+        TestStatus status = new TestStatus("JVMTI_THREAD_STATE_SLEEPING");
+        CountDownLatch ready = new CountDownLatch(1);
+        // Test thread exits by InterruptedException,
+        // stopFlag is to handle spurious wakeups.
+        final boolean[] stopFlag = new boolean[1];
+        Thread vthread = createPinnedVThread(() -> {
+            ready.countDown();
+            try {
+                while (!stopFlag[0]) {
+                    Thread.sleep(60000);
+                }
+            } catch (InterruptedException ex) {
+                // expected, ignore
+            }
+        });
+        vthread.start();
+        ready.await();
+
+        // Suspend test thread in "waiting" state.
+        suspendWaiting(vthread);
+
+        // vthread is suspended, set stopFlag before testThreadStates
+        stopFlag[0] = true;
+
+        // don't test interrupt() - it causes thread state change for parked thread
+        // even if it's suspended
+        testThreadStates(vthread, true, false,
+                JVMTI_THREAD_STATE_WAITING | JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT,
+                JVMTI_THREAD_STATE_SLEEPING | JVMTI_THREAD_STATE_PARKED);
+        status.print();
+    }
+
+    static void parked() throws Exception {
+        // JVMTI_THREAD_STATE_PARKED
+        // Thread is parked, for example: LockSupport.park, LockSupport.parkUtil and LockSupport.parkNanos.
+        TestStatus status = new TestStatus("JVMTI_THREAD_STATE_PARKED");
+        CountDownLatch ready = new CountDownLatch(1);
+        final boolean[] stopFlag = new boolean[1];
+
+        Thread vthread = createPinnedVThread(() -> {
+            ready.countDown();
+            while (!stopFlag[0]) {
+                LockSupport.park(Thread.currentThread());
+            }
+        });
+        vthread.start();
+        ready.await();
+
+        // Suspend test thread in "waiting" state.
+        suspendWaiting(vthread);
+
+        // vthread is suspended, set stopFlag before testThreadStates
+        stopFlag[0] = true;
+
+        // don't test interrupt() - it causes thread state change for parked thread
+        // even if it's suspended
+        testThreadStates(vthread, true, false,
+                JVMTI_THREAD_STATE_WAITING | JVMTI_THREAD_STATE_WAITING_INDEFINITELY | JVMTI_THREAD_STATE_PARKED);
+        // allow test thread to finish
+        LockSupport.unpark(vthread);
+        status.print();
+    }
+
+    static void inNative() throws Exception {
+        TestStatus status = new TestStatus("JVMTI_THREAD_STATE_IN_NATIVE");
+        Thread vthread = createPinnedVThread(() -> {
+            waitInNative();
+        });
+        vthread.start();
+        while (!waitInNativeReady) {
+            Thread.sleep(50);
+        }
+        testThreadStates(vthread, false, true,
+                JVMTI_THREAD_STATE_RUNNABLE | JVMTI_THREAD_STATE_IN_NATIVE,
+                0);
+        endWait();
+        status.print();
+    }
+
+
+    public static void main(String[] args) throws Exception {
+        runnable();
+        /* "waiting" test cases fail due JDK-8310584
+        blockedOnMonitorEnter();
+        waiting(false);
+        waiting(true);
+        sleeping();
+        parked();
+        */
+        inNative();
+
+        int errCount = getErrorCount();
+        if (errCount > 0) {
+            throw new RuntimeException("Test failed, " + errCount + " errors");
+        }
+    }
+
+    private static Thread createPinnedVThread(Runnable runnable) {
+        final Object syncObj = new Object();
+        return Thread.ofVirtual().unstarted(() -> {
+            synchronized (syncObj) {
+                runnable.run();
+            }
+        });
+    }
+
+    // Native implementation of suspendWaiting.
+    // Returns false if the method is not able to reach the desired state in several tries.
+    private static native boolean trySuspendInWaitingState(Thread vthread);
+
+    // Suspends virtual thread and ensures it's suspended in "waiting" state
+    // (to handle possible spurious wakeups).
+    // throws an exception if the method is not able to reach the desired state in several tries.
+    private static void suspendWaiting(Thread vthread) {
+        boolean result = trySuspendInWaitingState(vthread);
+        if (!result) {
+            throw new RuntimeException("Failed to suspend thread in WAITING state");
+        }
+    }
+
+    // Tests thread states (vthread and the carrier thread).
+    // expectedStrong specifies value which must be present in vthreat state;
+    // expectedWeak is a combination of bits which may be set in vthreat state
+    // (at least one of the bit must set, but not all).
+    // Note: Last steps of the testing are interrupt/resume the virtual thread,
+    // so after the call vthread is interrupted.
+    private static native void testThread(Thread vthread, boolean isVThreadSuspended,
+                                          boolean testInterrupt,
+                                          int expectedStrong, int expectedWeak);
+    private static native int getErrorCount();
+    // To retry test case when spurious wakeup detected.
+    private static native int resetErrorCount(int count);
+
+    private static boolean waitInNativeReady = false;
+
+    // Sets waitInNativeReady static field to true
+    // and then waits until endWait() method is called.
+    private static native void waitInNative();
+    // Signals waitInNative() to exit.
+    private static native void endWait();
+
+    private static void testThreadStates(Thread vthread, boolean isVThreadSuspended,
+                                         boolean testInterrupt,
+                                         int expectedStrong, int expectedWeak) {
+        String name = vthread.toString();
+        log("Thread " + name);
+        testThread(vthread, isVThreadSuspended, testInterrupt, expectedStrong, expectedWeak);
+    }
+
+    private static void testThreadStates(Thread vthread, boolean isVThreadSuspended,
+                                         boolean testInterrupt, int expectedState) {
+        testThreadStates(vthread, isVThreadSuspended, testInterrupt, expectedState, 0);
+    }
+
+    // helper class to print status of each test
+    private static class TestStatus {
+        private final String name;
+        private final int startErrorCount;
+        TestStatus(String name) {
+            this.name = name;
+            startErrorCount = getErrorCount();
+            log(">>" + name);
+        }
+        void print() {
+            log("<<" + name + (startErrorCount == getErrorCount() ? " - OK" : " - FAILED"));
+            log("");
+        }
+    }
+
+    private static void log(Object s) {
+        System.out.println(s);
+    }
+}